The present invention relates to a method for the cremation of bodies in coffins m a crematorium furnace, in whose walls at least one burner is arranged, which is supplied with fuel, and wherein the removal of the flue gas being generated during the cremation takes place via a conduit, and an installation for the cremation of bodies in coffins.
Today, such methods for cremation are subject to increased requirements for protecting the environment (i.e., 17th Federal Emission Protection Ordinance). This means that there are maximum values for the noxious material burden, which may not be exceeded. In accordance with the prior art, there is only the possibility of subjecting the flue gas released into the chimney to flue gas scrubbing. However, this is expensive. Often, it is not possible because of space considerations in the existing installations which are to be retrofitted.
Moreover, at the start of the combustion process, large amounts of carbon monoxide are generated by the burning of the coffin, which is made of wood, since because of the available portion of oxygen in the air used for the combustion, the amount of oxygen which would be required for the complete combustion of the carbon being generated in is phase of the cremation process is not available, even though at present operations are performed with air numbers of up to 3.5. Thus, at the start of burning, large loads of non-consumed CO are released. This is particularly unfortunate because CO leads to the formation of cancer-causing dibenzofuranes and dibenzodioxins.
Typically, the thermal output of such crematorium furnaces is approximately 550 to 600 KW, which corresponds to a net output of 60 standard cubic meters (Nm3) of natural gas per hour. This means that at an air number of 3.5 approximately 2200 Nm3 of flue gas per hour are being produced. The downstream-connected flue gas scrubbing components must be dimension correspondingly large.
The retrofitting of exiting installations which is demanded today is also problematic, because the existing crematoria are classified as historical monuments, so that structural changes are very difficult or even impossible to undertake.
The considerable amount of flue gas heat being created causes a further problem. While in some countries the waste heat is commercially used, this is not the case, for example in Germany, for reasons of piety.
A further problem of the flue gas in general lies in that nitrous oxides (NOx) are generated in the course of combustion with the use of natural air because of the heavy nitrogen content of the air (approximately 75%), and this at high air numbers in particular. This also makes the later cleaning of the waste gas necessary.
It is therefore an object of the present invention to further develop a method of the type mentioned at the outset in such a way that the noxious waste gases are reduced and the energy used increased. In the case of a retrofit, this should be achievable by possibly also increasing the efficiency of existing cremation installations.
This object is attained in accordance with the present invention in that cremation takes place in a crematorium furnace without a supply of natural air, in that at least half the flue gas leaving the crematorium furnace is conducted without being cooled to the crematorium chamber for creating a flue gas cycle, and in that oxygen is admixed with the flue gas in the flue gas cycle. The present invention fiber relates to several advantageous further developments.